Wide angle lens system having a distorted intermediate image

ABSTRACT

The wide angle lens system described herein allows projection devices (e.g., rear projection display devices) to be more compact than would otherwise be possible. The lens system includes a wide angle lens stage and a relay lens stage. When operating as a projection device, the relay lens stage projects a distorted intermediate image to the wide angle lens stage, which projects the image for display. The distortion cause by the relay lens stage compensates (i.e., is approximately equal and opposite) for the distortion caused by the wide angle stage. The distortion can be the image shape and/or the focal plane. When operating as a taking device, the wide angle stage provides a distorted image to the relay lens stage, which compensates for the distortion and provide a less distorted, or even non-distorted image, for capture.

RELATED APPLICATIONS

[0001] The present U.S. Patent application is related to U.S. patent application Ser. No. 10/______ (Atty. Docket No. P019), entitled “ULTRA THIN REAR PROJECTION DISPLAY” filed Aug. ______, 2002.

FIELD

[0002] The invention relates to lenses for use in optical devices. More particularly, the invention relates to lenses for use in optical devices employing wide angle lens systems.

BACKGROUND

[0003] In order to provide a television with a screen size greater than approximately 40 inches a display device other than a direct view cathode ray tube (CRT) is typically used. As the screen size of a CRT increases, so too does the depth. It is generally accepted that for screen sizes greater than 40 inches direct view CRTs are no longer practical. Two alternatives exist for large screen (>40 inch screen size) displays: projection displays and plasma displays.

[0004] Current plasma displays are much more expensive than projection displays. Plasma displays are generally thin enough to mount on a wall, but can be heavy enough that mounting can be difficult. For example, current 42 inch plasma displays can weigh 80 pounds or more and 60 inch plasma displays can weigh 150 pounds or more. One advantage of plasma displays over current projection displays is that plasma displays are typically much thinner than current projection displays having the same screen size.

[0005] Projection displays, specifically rear projection displays, are typically more cost-effective then plasma displays. Projection displays may also consume too much space in a room to provide a practical solution for large screen needs. For example, typical 60 inch rear projection displays are 24 inches thick and can weigh 200 to 300 pounds.

[0006]FIG. 1 illustrates a prior art rear projection display device. In general, display device 100 includes optical engine 140, projection lens 130, back plate mirror 120 and screen 110. Optical engine 140 generates an image to be projected on screen 110. projection lens 130 projects the image from optical engine 140 on to back plate mirror 120, which reflects the image to screen 110. The size of display device 100 is proportional to the size of the image to be displayed on screen 110. Thus, for large screen sizes (e.g., >60 inches), the overall size of display device 100 can be very large.

[0007] Thin rear projection display devices have been developed that are less than 12 inches thick. However, these thinner rear projection display devices typically rely on an aspherical mirror, which is difficult to manufacture and difficult to align. The difficulties associated with the aspherical mirror results in current thin rear projection displays being expensive, which restricts the availability of rear projection displays in desirable packages.

[0008]FIG. 2 illustrates a prior art thin rear projection display device with an aspherical mirror. An image from optical engine 260 is projected on reflective mirror 240 by projection lens 250. Reflective mirror 240 reflects the image to aspherical mirror 230, which magnifies the projected image and extends the field ray angle. Aspherical mirror 230 reflects the image to back plate mirror 220, which then reflects the image to screen 210. While rear projection display device 200 provides a thinner package for the same size screen as compared to display device 100 of FIG. 1, the manufacturing and alignment issues associated with use of aspherical mirror 230 greatly increases the cost of display device 200.

[0009] Another shortcoming of display device 200 is the angle of optical engine 260 with respect to mirrors 220, 230 and 240 and to screen 210. Without compensation, the angle of optical engine 260 results in a trapezoidal, or keystone, shaped image. The compensation associated with the angle to provide a square image further increases the cost and complexity of display device 200.

SUMMARY

[0010] In one embodiment, a lens system includes a first stage to create a distorted intermediate image and a second, wide angle lens stage that causes distortion to substantially cancel the distortion of the intermediate image and to project a substantially non-distorted image corresponding to the intermediate image.

BRIEF DESCRIPTION OF THE DRAWINGS

[0011] The invention is illustrated by way of example, and not by way of limitation, in the figures of the accompanying drawings in which like reference numerals refer to similar elements.

[0012]FIG. 1 illustrates a prior art rear projection display device.

[0013]FIG. 2 illustrates a prior art thin rear projection display device with an aspherical mirror.

[0014]FIG. 3 illustrates one embodiment of an ultra-thin rear projection display device with planar mirrors parallel to a screen.

[0015]FIG. 4 illustrates one embodiment of a folded wide angle lens system having a distorted intermediate image.

[0016]FIG. 5 illustrates one embodiment of a wide angle lens system having a distorted intermediate image.

[0017]FIG. 6 illustrates one embodiment of a rear projection display device with a wide angle lens system having an intermediate image.

DETAILED DESCRIPTION

[0018] Wide angle lens systems having a distorted intermediate image are described. In the following description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the invention. It will be apparent, however, to one skilled in the art that the invention can be practiced without these specific details. In other instances, structures and devices are shown in block diagram form in order to avoid obscuring the invention.

[0019] The wide angle lens system described herein allows projection devices (e.g., rear projection display devices) to be more compact than would otherwise be possible. The lens system includes a wide angle lens stage and a relay lens stage. When operating as a projection device, the relay lens stage projects a distorted intermediate image to the wide angle lens stage, which projects the image for display. The distortion caused by the relay lens stage compensates (i.e., is approximately equal and opposite) for the distortion caused by the wide angle stage. The distortion can be to the image shape and/or the focal plane. When operating as a taking device, the wide angle stage provides a distorted image to the relay lens stage, which compensates for the distortion and provides a less distorted, or even non-distorted image, for capture.

[0020]FIG. 3 illustrates one embodiment of a rear projection display device with planar mirrors parallel to a screen. As described in greater detail below, use of planar mirrors parallel to the screen as well as a wide angle projection lens having an optic axis that is perpendicular to the mirrors and the screen allows the rear projection display device to be thinner and simpler than prior art rear projection display devices. For example, an ultra-thin rear projection display device as described herein that is less than 7 inches thick can provide a 60 inch image.

[0021] In one embodiment, rear projection display device 300 includes screen 310, back plate mirror 320, intermediate mirror 330, lens system 340 and digital micromirror device (DMD) 350. Other components known in the art are not illustrated for reasons of simplicity of description. An image can be provided to DMD 350 in any manner known in the art. DMD 350 selectively reflects light from a light source (not shown in FIG. 3) to lens system 340. Any type of display device known in the art can be used in display device 300. Other types of devices (e.g., microelectromechanical systems (MEMS), grating light valve (GLV), liquid crystal display (LCD), liquid crystal on silicon (LCOS)) can be used to provide an image to lens system 340.

[0022] In one embodiment, DMD 350 is offset from the optic axis of lens system 340 such that only a portion (e.g., 50%, 60%, 40%) of the available lens field is used. By offsetting DMD 350 with respect to the optic axis of lens system 340, the image from DMD 350 is projected by lens system 340 in the upper portion of the lens field to intermediate mirror 330. Alternatively, a lower portion of the lens field can be used to project an image to intermediate mirror 330. In such an embodiment, lens system 340 would be above intermediate mirror 330, which would be above back plate mirror 320.

[0023] In order to project an image as described, lens system 340 is a very wide angle lens system. In one embodiment, lens system 340 has a field angle of 152° or more; however, other lenses can be used. In general, the wider the angle of lens system 340, the thinner display device 300 can be made. Description of a suitable wide angle lens system is described in greater detail below.

[0024] Intermediate mirror 330 reflects the image to back plate mirror 320, which reflects the image to screen 310, which can be, for example, a Fresnel lens. Back plate mirror 320 is also a planar mirror and is parallel to screen 310 and perpendicular to the optic axis of lens system 340. Because the optic axis of lens system 340 is perpendicular to intermediate mirror 330 and both intermediate mirror 330 and back plate mirror 320 are planar and parallel to screen 310, the distortion caused by angled lenses and aspherical mirrors is absent in display device 300. This simplifies the design of display device 300 and reduces the cost and complexity of manufacturing. Embodiments of a rear projection display device in which the wide angle lens system described herein can be used is described in greater detail in the above-referenced patent application, which is incorporated by reference.

[0025]FIG. 4 illustrates one embodiment of a folded wide angle lens system having a distorted intermediate image. While the lens system of FIG. 4 is described as a projection lens system, the lens system can also be used for image capture, for example, by a camera.

[0026] DMD 410 provides an image to the lens system. As described above, other types of devices can be used to provide an image to the lens system. Prism 420 directs the image to relay lens group 430. Relay lens group 430 projects the image from prism 420 to prism 440 and distorts the image such that intermediate prism 440 receives an intentionally distorted intermediate image.

[0027] In one embodiment, relay lens group 430 includes 9 lenses; however, any number of lenses can be used based on, for example, the desired distortion of the intermediate image, or the overall size of the lens system. The distortion to be caused by relay lens group 430 is equal and opposite the distortion caused by wide angle lens group 450. In one embodiment, the intermediate image is approximately a half circle image in a warped image plane. In alternate embodiments, other types of distortion can be used. For example, if the full lens field is to be used, the distorted intermediate image would be a generally circular image. The image plane may or may not be warped.

[0028] Intermediate prism 440 provides a 90° fold of the image path. As described below with respect to FIG. 5, the fold is not required. Alternatively, other fold angles, for example, 45°, 30°, 135° could be used. Wide angle lens group 450 projects the distorted intermediate image to a screen for display. Because wide angle lens group 450 causes distortion to the image to be projected and the intermediate image has been pre-distorted by relay lens group 430, the resulting image projected by the lens system has little or no distortion. In one embodiment, the total distortion caused by relay lens group 430, wide angle lens group 450 and any associated prisms is less than 3%.

[0029] In one embodiment, the optic axes of the lenses of relay lens group 430 are aligned. Similarly, the optic axes of the lenses of wide angle lens group 450 are also aligned. Wide angle lens group provides a field angle of greater than 100°. In one embodiment the field angle is 153°; however, any angle can be provided. In one embodiment, the optical axis of wide angle lens group 450 is perpendicular to the screen so that keystone, or trapezoidal, distortion is absent.

[0030]FIG. 5 illustrates one embodiment of a wide angle lens system having a distorted intermediate image. The lens system of FIG. 5 is similar to the lens system of FIG. 4 except that the lens system of FIG. 5 is not folded. That is, wide angle lens system 450 is co-axial with relay lens system 430. The lens system of FIG. 5 does not include an intermediate prism. An intermediate prism can be included, if desired.

[0031] In one embodiment, the lens system of FIG. 5 has the following prescription: Surface RDY THI RMD GLA  1: 46.74531  4.000000 NBF1_HOYA  2: 28.81163  5.051213  3: 30.58292  4.000000 NBFD10_HOYA  4: 21.01576  8.441106  5: 129.13928  4.000000 SLAM60_OHARA ASP: K: 0.000000 IC: YES CUF: 0.000000 A: 0.664982E−04 B: −.187975E−06 C: 0.420794E−09 D: −.348519E−12  6: 21.14941  8.859193 ASP: K: 0.000000 IC: YES CUF: 0.000000 A: −.367450E−04 B: 0.130594E−06 C: −.665374E−09 D: 0.794813E−12  7: 78.00018  3.124861 FDS90_HOYA  8: 16.67079  9.473114 BACD16_HOYA  9: −13.03245  0.200000 10: −17.74399  6.650512 MNBF1_HOYA ASP: K: 0.000000 IC: YES CUF: 0.000000 A: 0.314557E−03 B: −.254460E−05 C: 0.149709E−07 D: −.573297E−10 11: −14.40905  0.200000 ASP: K: 0.000000 IC: YES CUF: 0.000000 A: −.440469E−04 B: 0.237538E−05 C: −.134637E−07 D: 0.222969E−10 12: 131.97096  6.000000 MNBF1_HOYA ASP: K: 0.000000 IC: YES CUF: 0.000000 A: 0.711368E−04 B: −.624364E−06 C: 0.210000E−08 D: −.350000E−11 13: −15.59413  2.000000 ASP: K: 0.000000 IC: YES CUF: 0.000000 A: 0.257396E−03 B: −.884746E−06 C: 0.186450E−08 D: 0.216077E−11 14: INFINITY 30.000000 FD60_HOYA 15: INFINITY 24.565488 16: −64.35637  4.999034 FD60_HOYA 17: −1966.99974  5.494742 18: −96.81620 16.104081 NBFD13_HOYA 19: −39.51766  0.200000 20: 136.11245 14.269098 LAC8_HOYA 21: −114.50422 39.301091 22: −250.53752  5.915028 BACD16_HOYA 23: −62.97973 24.296450 STO:   8.12022  3.000000 FDS90_HOYA 25: 7.27512  2.000000 26: −67.85690  5.522870 BACD16_HOYA 27: −5.88750  7.902370 FDS90_HOYA 28: 135.96725  1.688647 29: −35.98083 10.637917 MNBF1_HOYA ASP: K: 0.000000 IC: YES CUF: 0.000000 A: 0.956626E−04 B: 0.298084E−06 C: −.100781E−07 D: 0.371253E−10 30: −16.84259  0.200000 ASP: K: 0.000000 IC: YES CUF: 0.000000 A: 0.434637E−04 B: 0.131005E−06 C: −.120433E−08 D: 0.718134E−12 31: 29.02346  8.028674 SLAH60_OHARA ASP: K: 0.000000 IC: YES CUF: 0.000000 A: 0.696210E−05 B: −.847612E−07 C: 0.104328E−09 D: −.182720E−12 32: 186.81664  4.000000 ASP: K: 0.000000 IC: YES CUF: 0.000000 A: −.196461E−05 B: 0.343490E−07 C: −.146991E−09 D: 0.000000E+00 33: INFINITY 21.000000 BSC7_HOYA 34: INFINITY  2.000000 35: INFINITY  3.000000 FC5_HOYA 36: INFINITY  0.440000

[0032] In the above prescription, surfaces 1-13 correspond to wide angle lens group 450 and surfaces 16-32 correspond to relay lens group 430. In alternate embodiments, other prescriptions and/or other materials can also be used.

[0033]FIG. 6 illustrates one embodiment of a rear projection display device having a wide angle lens. Display device 600 includes screen 610, wide angle lens system 620 and DMD 630. In one embodiment, screen 610 is a Fresnel lens as described in greater detail in the related application referenced above, which is incorporated by reference herein.

[0034] An image is generated a provided by optical engine components (not shown in FIG. 6) that are known in the art and directed to wide angle lens system 620 via DMD 630. In alternate embodiments, DMD 630 can be replaced by other components, for example, microelectromechanical systems (MEMS), grating light valves (GLV), liquid crystal display (LCD), liquid crystal on silicon (LCOS), etc. The optic axis of DMD 630 is aligned with the optic axis of wide angle lens system 620 so that the full lens field is used to project the image to screen 610.

[0035] As described herein, an image is projected on a screen through a wide angle lens system. The screen can be a Fresnel lens. However, many other objects can operate as a screen for purposes of displaying an image. In general, any object that diffuses light can be used as a screen. For example, a wall, water or fog can be used as a screen.

[0036] Reference in the specification to “one embodiment” or “an embodiment” means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the invention. The appearances of the phrase “in one embodiment” in various places in the specification are not necessarily all referring to the same embodiment.

[0037] In the foregoing specification, the invention has been described with reference to specific embodiments thereof. It will, however, be evident that various modifications and changes can be made thereto without departing from the broader spirit and scope of the invention. The specification and drawings are, accordingly, to be regarded in an illustrative rather than a restrictive sense. 

What is claimed is:
 1. A lens system comprising: a first stage to create a distorted intermediate image; and a second, wide angle lens stage that causes distortion to substantially cancel the distortion of the intermediate image and to project a substantially non-distorted image corresponding to the intermediate image.
 2. The lens system of claim 1 wherein the first stage comprises lenses according to: Surface RDY THI  1: −64.35637  4.999034  2: −1966.99974  5.494742  3: −96.81620 16.104081  4: −39.51766  0.200000  5: 136.11245 14.269098  6: −114.50422 39.301091  7: −250.53752  5.915028  8: −62.97973 24.296450 STO:   8.12022  3.000000  8: 7.27512  2.000000  9: −67.85690  5.522870 10: −5.88750  7.902370 11: 135.96725  1.688647 12: −35.98083 10.637917 ASP: K: 0.000000 IC: YES CUF: 0.000000 A: 0.956626E−04 B: 0.298084E−06 C: −.100781E−07 D: 0.371253E−10 13: −16.84259  0.200000 ASP: K: 0.000000 IC: YES CUF: 0.000000 A: 0.434637E−04 B: 0.131005E−06 C: −.120433E−08 D: 0.718134E−12 14: 29.02346  8.028674 ASP: K: 0.000000 IC: YES CUF: 0.000000 A: 0.696210E−05 B: −.847612E−07 C: 0.104328E−09 D: −.182720E−12 15: 186.81664  4.000000 ASP: K: 0.000000 IC: YES CUF: 0.000000 A: −.196461E−05 B: 0.343490E−07 C: −.146991E−09 D: 0.000000E+00.


3. The lens system of claim 1 wherein the second stage comprises lenses according to: Surface RDY THI  1: 46.74531 4.000000  2: 28.81163 5.051213  3: 30.58292 4.000000  4: 21.01576 8.441106  5: 129.13928 4.000000 ASP: K: 0.000000 IC: YES CUF: 0.000000 A: 0.664982E−04 B: −.187975E−06 C: 0.420794E−09 D: −.348519E−12  6: 21.14941 8.859193 ASP: K: 0.000000 IC: YES CUF: 0.000000 A: −.367450E−04 B: 0.130594E−06 C: −.665374E−09 D: 0.794813E−12 7: 78.00018 3.124861  8: 16.67079 9.473114  9: −13.03245 0.200000 10: −17.74399 6.650512 ASP: K: 0.000000 IC: YES CUF: 0.000000 A: 0.314557E−03 B: −.254460E−05 C: 0.149709E−07 D: −.573297E−10 11: −14.40905 0.200000 ASP: K: 0.000000 IC: YES CUF: 0.000000 A: −.440469E−04 B: 0.237538E−05 C: −.134637E−07 D: 0.222969E−10 12: 131.97096 6.000000 ASP: K: 0.000000 IC: YES CUF: 0.000000 A: 0.711368E−04 B: −.624364E−06 C: 0.210000E−08 D: −.350000E−11 13: −15.59413 2.000000 ASP: K: 0.000000 IC: YES CUF: 0.000000 A: 0.257396E−03 B: −.884746E−06 C: 0.186450E−08 D: 0.216077E−11.


4. The lens system of claim 1 wherein the first stage and the second stage are co-axial.
 5. The lens system of claim 1 wherein the optic axis of the first stage and the optic axis of the second stage form an angle.
 6. The lens system of claim 5 wherein the lenses of the first stage are co-axial and the lenses of the second stage are co-axial.
 7. The lens system of claim 5 wherein the angle is approximately 90°.
 8. The lens system of claim 5 wherein the angle is substantially less than 90°.
 9. The lens system of claim 5 wherein the angle is substantially greater than 90°.
 10. The lens system of claim 1 wherein the wide angle is greater than 100° full field.
 11. The lens system of claim 1 wherein the distortion is less than 3%.
 12. The lens system of claim 1 wherein the relative illumination of the extreme angles is greater than 30%.
 13. A display device comprising: a screen; and a wide angle lens system having a first stage to create a distorted intermediate image and a second, wide angle lens stage that causes distortion to substantially cancel the distortion of the intermediate image and to project a substantially non-distorted image corresponding to the intermediate image on the screen.
 14. The display device of claim 13 further comprising a substantially planar back plate mirror to reflect the image to the screen, wherein the back plate mirror is substantially perpendicular to the optic axis of the wide angle lens system and substantially parallel to the screen.
 15. The display device of claim 14 further comprising a substantially planar intermediate mirror to reflect the image projected by the wide angle lens system to the back plate mirror, the intermediate mirror being parallel to the back plate mirror.
 16. The display device of claim 13 wherein the screen comprises a total internal reflection (TIR) Fresnel lens.
 17. The display device of claim 13 wherein the screen comprises a refractive Fresnel lens.
 18. The display device of claim 13 wherein the wide angle lens system projects the image using approximately one-half of the lens field.
 19. The display device of claim 13 wherein the wide angle lens system projects the image using less than one-half of the lens field.
 20. The display device of claim 13 further comprising a microelectromechanical system (MEMS) to provide the image to the wide angle lens system.
 21. The display device of claim 20 further comprising a digital micromirror device (DMD) to provide the image to the wide angle lens system.
 22. The display device of claim 13 further comprising a grating light valve (GLV) to provide the image to the wide angle lens system.
 23. The display device of claim 13 further comprising a liquid crystal display (LCD) to provide the image to the wide angle lens system.
 24. The display device of claim 23 further comprising a liquid crystal on silicon (LCOS) display to provide the image to the wide angle lens system.
 25. An apparatus comprising: an image capture device; and a wide angle lens system to create a distorted intermediate image and a relay lens stage that causes distortion to substantially cancel the distortion of the intermediate image and to project a substantially non-distorted image corresponding to the intermediate image to the image capture device.
 26. The apparatus of claim 25 wherein the relay lens stage and the wide angle lens stage are co-axial.
 27. The apparatus of claim 25 wherein the optic axis of the first stage and the optic axis of the second stage form an angle.
 28. The apparatus of claim 27 wherein the angle is approximately 90°.
 29. The apparatus of claim 27 wherein the angle is substantially less than 90°.
 30. The apparatus of claim 27 wherein the angle is substantially greater than 90°.
 31. The apparatus of claim 25 wherein the wide angle lens provides greater than 100° full field.
 32. The apparatus of claim 25 wherein the lens system causes less than 3% distortion.
 33. A method comprising: projecting an image with a relay lens group to generate a distorted intermediate image; and projecting the distorted intermediate image with a wide angle lens group to generate a substantially non-distorted final image, wherein the distortion caused by the first lens group is substantially equal and opposite the distortion caused by the second lens group.
 34. The method of claim 33 wherein the wide angle lens group comprises lenses according to: Surface RDY THI  1: −64.35637  4.999034  2: −1966.99974  5.494742  3: −96.81620 16.104081  4: −39.51766  0.200000  5: 136.11245 14.269098  6: −114.50422 39.301091  7: −250.53752  5.915028  8: −62.97973 24.296450 STO:   8.12022  3.000000  8: 7.27512  2.000000  9: −67.85690  5.522870 10: −5.88750  7.902370 11: 135.96725  1.688647 12: −35.98083 10.637917 ASP: K: 0.000000 IC: YES CUF: 0.000000 A: 0.956626E−04 B: 0.298084E−06 C: −.100781E−07 D: 0.371253E−10 13: −16.84259  0.200000 ASP: K: 0.000000 IC: YES CUF: 0.000000 A: 0.434637E−04 B: 0.131005E−06 C: −.120433E−08 D: 0.718134E−12 14: 29.02346  8.028674 ASP: K: 0.000000 IC: YES CUF: 0.000000 A: 0.696210E−05 B: −.847612E−07 C: 0.104328E−09 D: −.182720E−12 15: 186.81664 4.000000 ASP: K: 0.000000 IC: YES CUF: 0.000000 A: −.196461E−05 B: 0.343490E−07 C: −.146991E−09 D: 0.000000E+00.


35. The lens system of claim 33 wherein the relay lens group comprises lenses according to: Surface RDY THI  1: 46.74531 4.000000  2: 28.81163 5.051213  3: 30.58292 4.000000  4: 21.01576 8.441106  5: 129.13928 4.000000 ASP: K: 0.000000 IC: YES CUF: 0.000000 A: 0.664982E−04 B: −.187975E−06 C: 0.420794E−09 D: −.348519E−12  6: 21.14941 8.859193 ASP: K: 0.000000 IC: YES CUF: 0.000000 A: −.367450E−04 B: 0.130594E−06 C: −.665374E−09 D: 0.794813E−12  7: 78.00018 3.124861  8: 16.67079 9.473114  9: −13.03245 0.200000 10: −17.74399 6.650512 ASP: K: 0.000000 IC: YES CUF: 0.000000 A: 0.314557E−03 B: −.254460E−05 C: 0.149709E−07 D: −.573297E−10 11: −14.40905 0.200000 ASP: K: 0.000000 IC: YES CUF: 0.000000 A: −.440469E−04 B: 0.237538E−05 C: −.134637E−07 D: 0.222969E−10 12: 131.97096 6.000000 ASP: K: 0.000000 IC: YES CUF: 0.000000 A: 0.711368E−04 B: −.624364E−06 C: 0.210000E−08 D: −.350000E−11 13: −15.59413 2.000000 ASP: K: 0.000000 IC: YES CUF: 0.000000 A: 0.257396E−03 B: −.884746E−06 C: 0.186450E−08 D: 0.216077E−11.


36. The method of claim 33 wherein the first stage and the second stage are co-axial.
 37. The method of claim 33 wherein the wide angle is greater than 100° full field.
 38. The method of claim 33 wherein the distortion is less than 3%.
 39. A lens system comprising: a relay lens group to create a distorted intermediate image; and a wide angle lens group providing a field of at least 100° that causes distortion to substantially cancel the distortion of the intermediate image and to project an image having less than 3% distortion corresponding to the intermediate image.
 40. The lens system of claim 39 wherein all lenses of the relay lens group are co-axial.
 41. The lens system of claim 40 wherein all lenses of the wide angle lens group are co-axial.
 42. The lens system of claim 41 wherein the wide angle lens group and the relay lens group are co-axial.
 43. The lens system of claim 41 wherein the optic axis of the wide angle lens group and the optic axis of the relay lens group form an angle.
 44. The lens system of claim 43 wherein the angle is approximately 90°.
 45. The lens system of claim 43 wherein the angle is substantially less than 90°.
 46. The lens system of claim 43 wherein the angle is substantially greater than 90°. 